Magnetically actuated clutch assembly

ABSTRACT

A clutch assembly includes a first clutch including a cam plate, a pocket plate and axially pivoting struts that drivably connect the plates for rotation in a first rotary direction, and disconnect the plates when the cam plate rotates in a second direction relative to the pocket plate, and a second clutch including a first cam plate, a first pocket plate, a coil and first struts that drivably connect the first cam plate and the first pocket plate for rotation in the second direction and disconnect the first cam plate and the first pocket plate when the coil is energized and the first cam plate rotates in the first direction relative to the first pocket plate.

CROSS REFERENCE TO RELATED APPLICATIONS

The present patent application claims the benefit of and is a divisionalof U.S. patent application Ser. No. 12/914,122, filed Oct. 28, 2010,which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a one-way clutch, particularly to aone-way clutch, whose states of engagement and disengagement arecontrolled electromagnetically by axially pivoting a locking element.

2. Description of the Prior Art

A conventional one-way clutch (OWC) overruns when one of its racesrotates in one direction relative to the other race, and it engages orlocks in the other direction. Such clutches provide no control overtheir operation, i.e., whether they lockup or rotate in the lockupdirection.

There are, however, functional requirements wherein a one-way clutchcould provide a new, wider range of functions if control were provided.For example, it is desirable to have a OWC overrun in either rotarydirection until a command causes the clutch to lockup. In anotherinstance, it is desirable for a OWC that conventionally overruns in onedirection and locks in the other to lockup in both rotary directions.

In another example of enhanced functionality, a OWC could be made tooverrun in either rotary direction until a command causes the clutch tolock during clockwise rotation, or to lockup during counterclockwiserotation, or to lockup in both directions.

A need exists in the industry for a one-way clutch that could becontrolled such that it would perform such desired functions.

SUMMARY OF THE INVENTION

A clutch assembly includes a first clutch including a cam plate, apocket plate and axially pivoting struts that drivably connect theplates for rotation in a first rotary direction, and disconnect theplates when the cam plate rotates in a second direction relative to thepocket plate, and a second clutch including a first cam plate, a firstpocket plate, a coil and first struts that drivably connect the firstcam plate and the first pocket plate for rotation in the seconddirection and disconnect the first cam plate and the first pocket platewhen the coil is energized and the first cam plate rotates in the firstdirection relative to the first pocket plate.

By using two cam sets, one oriented to allow clockwise lockup, the otherto allow counterclockwise lockup, the clutch can be controlled tooverrun in both directions, to lock in either direction or to lock inboth directions.

The scope of applicability of the preferred embodiment will becomeapparent from the following detailed description, claims and drawings.It should be understood, that the description and specific examples,although indicating preferred embodiments of the invention, are given byway of illustration only. Various changes and modifications to thedescribed embodiments and examples will become apparent to those skilledin the art.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more readily understood by reference to thefollowing description, taken with the accompanying drawings, in which:

FIG. 1 is a front perspective view of a magnetic diode assembly;

FIG. 2 is a rear perspective view of the magnetic diode assembly of FIG.1;

FIG. 3 is a cross sectional side view of the diode assembly showing thecomponents spaced apart;

FIG. 4 is a cross sectional side view of the diode assembly showing astrut engaged with a notch;

FIG. 5 is perspective view showing the rear face of the pocket plate;

FIG. 6 is perspective view of a strut;

FIG. 7 is a side perspective view of an alternate diode assembly;

FIG. 8 is a side cross sectional view of an alternate strut for assemblyof FIG. 7;

FIG. 9 is a side cross sectional view of an alternate diode assembly;

FIG. 10 is a top perspective view of a cam plate for the diode of FIG.9;

FIG. 11 is a side cross sectional view of an alternate diode assemblyhaving a coil in the cam plate and a coil in the pocket plate;

FIG. 12 is perspective cross section showing the magnetic diode of FIGS.1-3 and a mechanical diode assembled in an automatic transmission case;

FIG. 13 is perspective cross section showing an alternate magnetic diodehaving two set of oppositely directed cams assembled in an automatictransmission case;

FIG. 14 is perspective top view in cross section of the pocket plate ofthe diode of FIG. 13; and

FIG. 15 is perspective top view of the cam plate of the diode of FIG.13.

DETAILED DESCRIPTION

Referring now to FIGS. 1-4, a magnetic diode assembly 10, i.e., amagnetically actuated one-way clutch, includes a cam plate 12; a pocketplate 14, encircling the cam plate, formed with a circular recess 13concentric about an axis and including a portion fitted into the recess13; a snap ring 16 fitted into a groove 17 in plate 14 for securing thetwo plates together; and a bobbin 18 containing an coil of electricallyconductive wire 19 fitted in a groove 20 formed in rear surface of thepocket plate. The radial inner surface of cam plate 12 is formed withaxially directed spline teeth 22, and the radial outer surface of pocketplate 14 is formed with axially directed spline teeth 24.

Cam plate 12 is formed with a series of cams 26 spaced about a centrallongitudinal axis 28, which is concentric with recess 13.

Pocket plate 14 is formed with a series of pockets 30, spaced about axis28, each pocket containing a strut 32 and a spring 34, which continuallyurges the respective strut to pivot along axis 28 into contact with thecams, such that the strut can engage one of the notches 36.

FIG. 4 is a cross sectional side view of the diode assembly 10 showing astrut 32 engaged with the notch 36 of a cam 26 while the coil 19 isdeenergized. When the coil 19 is energized with electric current theresulting electromagnetic field produces a force on the strut 32, whichexceeds the force of spring 34, thereby pulling the strut along axis 28away from the notch 36 and cam 26. The struts 32 pivot axially towardthe cams 26 in response to actuation by the magnetic field.

FIG. 5 is perspective view showing an inner face 40 of pocket plate 14formed with a series of pockets 30.

FIG. 6 is perspective front view of a strut 32 showing the front face42; which faces the cams 26 in the assembled position; a lockup face 44,which engages by contact the notch 36 of a cam 26; pivot arms 46, 48,which pivot in the pockets 30 of the pocket plate 14; and a lowersurface, which faces the spring 34 and lower surface of the pocket 30 inthe assembled position.

Each strut 32 is magnetically permeable, not a permanent magnet, therebycausing the struts to react to the magnetic field produced when coil 19is energized with electric current. Each spring 34 is made frommagnetically impermeable stainless steel, such that the electromagneticfield has little effect on the springs. The spring 34 pushes the strut32 toward the cams 26.

The pocket plate 14 is made from a stainless steel alloy that isnon-permeable. The pocket plate will have no effect on the magneticfield or forces if it is made from such a material. To the magnet, thepocket plate doesn't exist. The cams are also made from non-permeablestainless steel to keep the strut 32 from magnetically “latching” to thecams when the coil 19 is energized. The snap ring 16 is made preferablyfrom magnetically permeable material.

In operation, when coil 19 is deenergized and cam plate 12 rotates inthe direction of arrow A relative to pocket plate 14, springs 34 pivotsstruts 32 into contact with cams 26 causing at least one of the strut 32to engage a notch 36 and the plates 12, 14 to rotate as a unit. Whencoil 19, which is embedded in the pocket plate 14, is energized withelectric current in response to a command to disengage the magneticdiode 10, an electromagnetic field pulls the struts 32 away fromengagement with the cam plate 12 overcoming the spring force andallowing the magnetic diode to overrun in either rotary direction.

When diode 10 overruns, a drag force between the cam plate 12 and struts32 tends to pull the struts tangentially. This force is directed fromthe pivot arms 46, 48 toward the lockup face 44 of the struts 32. Whenthe struts 32 engage the notches 36, snap ring 16 reacts a force tendingto separate the pocket plate 14 from cam plate 12, thereby keeping theplates within a preferred distance of each other when the magnetic diode10 is locked-up.

In the magnetic diode 58 of FIG. 7, a compression spring 60 located in apocket 30′ applies a force A to an alternate strut 62 tending to pivotthe strut axially clockwise away from cams 26, thereby unlocking thediode. When the coil 19 located in groove 20 is energized, strut 62 ispulled by the magnetic field causing the strut to pivot axiallycounterclockwise on the pocket plate toward the cams 26 and intoengagement with a notch 36, thereby locking the diode.

FIG. 8 shows that the lower surface of strut 62 is formed with a post64, which maintains spring 60 in its correct position; and an attractor66, which extends axially toward the coil 19. Strut 62 includes pivotarms 46, 48, which pivot in the pockets 30 of the pocket plate 14; alockup face 44, which engages by contact the notch 36 of a cam 26; pivotarms 46, 48, which pivot in the pockets 30 of the pocket plate 14; and alower surface 50, which faces the surface of the pocket 30 in theassembled position. The proximity of the attractor 66 to the coil 19 ascompared to that of surface 50 causes the magnetic force B to pivot thestrut 62 clockwise against the spring force, compressing spring 60,unlocking the diode and allowing it to overrun.

As shown in the cam plate 12′ of FIGS. 9 and 10, the coil 19 (not shown)of an alternate magnetic diode 70 is embedded in a groove 72 formed onthe axially opposite side of the cam plate 12′ from the location of thecams 26 and notches 36. Each spring 74, carried in the cam plate 14,produces a force A tending to pivot a strut 76 axially away from the camplate 12′, thereby unlocking the magnetic diode 70 and allowing it tooverrun. When coil 19 is energized, each strut 32 is pulled by themagnetic force B such that the strut pivots axially into the pocketplate 12 against the spring forces, thereby locking the magnetic diode70.

In the alternate diode assembly of FIG. 11, cam plate 12′ includesgroove 72 containing a bobbin 18 and a coil 19. Pocket plate 14 includesa groove 20 containing bobbin 18 and its coil 19. Each coil 19 isenergized independently. The coil 19 in the pocket plate 14 pivots astrut 32 axially into the pocket 30 and away from cams 26, i.e., in theunlocked or disengaged state. The coil 19 in the cam plate 12′ pivots astrut 32 axially toward the cams 26 and engagement with a notch 36,i.e., in the locked or engaged state. The magnetic forces produced bycoils 19 may be assisted by spring forces.

FIG. 12 is perspective cross section showing the magnetic diode 50assembled in an automatic transmission case 82, such that the externalspline 24 of pocket plate 14 engages an internal spline 86 formed in thecase 82. A mechanical diode 84 is installed axially adjacent magneticdiode 50 in the automatic transmission case 82, such that the externalspline 86 of its pocket plate 88 engages an internal spline 90 formed inthe case 82.

Mechanical diode 84 includes a snap ring, which secures its cam plate 94to the pocket plate 88. The pocket plates 14, 88 do not rotate due theirsplined connection to the case 82. The cam plates 12, 94 are secured bysplines 22, 96 to a member of the transmission that is supported forrotation.

The pocket plate 88 of mechanical diode 84 includes a series ofangularly spaced pockets, each containing a strut and a spring, whichurges a respective strut to pivot into engagement with the cams formedon the cam plate 94. When cam plate 94 rotates clockwise relative topocket plate 94, mechanical diode 84 locks. When cam plate 94 rotatescounterclockwise relative to pocket plate 94, mechanical diode 84overruns. Of course, the rotational direction that causes diode 84 tolock and overrun can be reversed by changing the cams.

When the coil 19 of magnetic diode 10 is deenergized, magnetic diode 10is engaged or locked, thereby holding the rotating member of thetransmission that is engaged with spline 22 against rotation on the case82 when cam plate 12 tends to rotate counterclockwise relative to pocketplate 14. When coil 19 is energized with electric current, magneticdiode 10 overruns when cam plate 12 rotates clockwise relative to pocketplate 14.

By positioning the two one-way clutches 10, 84 side-by-side along axis28, one of the clutches locks when the rotation member of thetransmission rotates clockwise and the other clutch locks-up when therotation member of the transmission rotates counterclockwise. In thisway the clutches 10, 84 alternately allow (i) free rotation in eitherrotary direction, (ii) lock in one rotary direction in response toenergizing the coil of the magnetic diode 10, and (iii) lock in bothrotary directions.

FIGS. 13 is a perspective cross section showing a magnetic diode 100assembled in an automatic transmission case 82, such that the externalspline 24 of pocket plate 102 engages an internal spline 86 formed inthe case 82.

As FIG. 14 shows, pocket plate 102 includes a radial outer series ofangularly spaced pockets 104, each pocket 104 containing a magneticallypermeably strut 32, 62 supported to pivot axially counterclockwisetoward a cam plate 106 in response to the force produced by a springlocated in the pocket, such as spring 34 shown in FIG. 3. Pocket plate102 also includes a radial inner series of angularly spaced pockets 108,each pocket 108 containing a magnetically impermeably strut 32, 62supported to pivot axially clockwise toward cam plate 106 in response tothe force produced by a spring located in the pocket.

As FIG. 15 shows, cam plate 106 includes a radial outer series ofangularly spaced cams 110 located for contact with the struts in pockets104 when the struts 32, 62 pivot toward the cams 110, and notches 112for engagement with the struts in pockets 104. Cam plate 106 alsoincludes a radial inner series of angularly spaced cams 114 located forcontact with the struts 32, 62 in pockets 108 when the struts pivottoward the cams 114, and notches 112 for engagement with the struts inpockets 108.

Cams 110 are inclined in an opposite direction from the slope of cams114 such that the struts 32, 62 in pockets 104, when pivoted to engagenotches 112, lock the one-way diode 100 when the cam plate rotates in afirst direction relative to the pocket plate 102, the inner set of cams114 overrunning the struts in pockets 108. Similarly, the struts 32, 62in pockets 108, when pivoted to engage notches 116, lock the one-waydiode 100 when the cam plate rotates in the opposite direction relativeto the pocket plate 102, the outer set of cams 110 overrunning thestruts in the pockets 104.

A bobbin 18 containing a coil 19 is fitted in groove 20, which is formedin pocket plate 102 and aligned with pockets 104, cams 110 and notches112. When coil 19 is energized with electric current, the magneticallypermeable struts 32 located in pockets 104 are pivoted into pockets 104and away from engagement with the notches 112 by the induced magneticfield, thereby unlocking clutch 100. When coil 19 is energized withelectric current, the magnetically impermeable struts located in pockets108 are unaffected by the induced magnetic field.

By using two cam sets, one oriented to allow clockwise lockup, the otherto allow counterclockwise lockup (effectively 2 OWC's butted togetherbut oriented to lock up in opposite directions to each other), theclutch can be controlled to overrun in both directions, to lock ineither direction or to lock in both directions.

In accordance with the provisions of the patent statutes, the preferredembodiment has been described. However, it should be noted that thealternate embodiments can be practiced otherwise than as specificallyillustrated and described.

1. A clutch assembly, comprising: a first clutch including a cam plate,a pocket plate and axially pivoting struts that drivably connect theplates for rotation in a first rotary direction, and disconnect theplates when the cam plate rotates in a second direction relative to thepocket plate; a second clutch including a first cam plate, a firstpocket plate, a coil and first struts that drivably connect the firstcam plate and the first pocket plate for rotation in the seconddirection and disconnect the first cam plate and the first pocket platewhen the coil is energized and the first cam plate rotates in the firstdirection relative to the first pocket plate.
 2. The assembly of claim1, further comprising: springs urging the struts to pivot axially towardengagement with cams formed on the cam plate.
 3. The assembly of claim1, further comprising: first springs urging the first struts to pivotaxially in a first pivot direction that is opposite an axial pivotdirection of the first struts caused by energizing the coil.
 4. Theclutch of claim 1, wherein: cams formed on a surface of the first camplate face the second plate; pockets formed on a surface of the firstpocket plate face the cams; and a spring urging a first strut to pivotaxially toward contact with the cams.
 5. The clutch of claim 1, wherein:cams formed on a surface of the first cam plate face the second plate;pockets formed on a surface of the first pocket plate face the cams; anda spring urging a first strut to pivot axially away from contact withthe cams.
 6. A clutch assembly, comprising: a first clutch including acam plate, a pocket plate and axially pivoting struts that drivablyconnect the plates for rotation in a first rotary direction, anddisconnect the plates when the cam plate rotates in a second directionrelative to the pocket plate; a second clutch including a first camplate, a first pocket plate, a coil and first struts that drivablyconnect the first cam plate and the first pocket plate for rotation inthe second direction and disconnect the first cam plate and the firstpocket plate when the coil is energized and the first cam plate rotatesin the first direction relative to the first pocket plate; cams formedon a surface of the first cam plate face the second plate; pocketsformed on a surface of the first pocket plate face the cams; a springurging a first strut to pivot axially toward contact with the cams; anda second spring urging a first strut to pivot axially away from contactwith the cams.